I personally don't think you should train SB on a guard, and you definitely don't need to train Rebounding.
I dont agree with you.
Fact is, there is no proper answer to the question about SB or RB, but this game is about matchups. You can win it by RB matchup as well. Once your PG will collect 7 REBs more than your opponent´s PG than you have hell of an advantage over him! You can win your game by having IS20 but would you advice to train it? Question is how other skills are trained, what potential your player is etc. As everything there are many ways to succes, some are cheaper, some are faster it is up to you which way you chose.
The same applies to blocks, but here there is so much undiscovered. It looks like blocks force opponent to look for player with lower blocks to go over him. Once you fill up your roster with blocks what is going to happen? Do we know? What skills are going to be crippled once you chose to train SB? Is it worth it? Where is the balance?
1 BBB, 23 Leagues, 11 Tournaments, 3 Europe Titles (SVK), 2 World Bronzes (SVK), 2 Europe Bronzes (SVK,FRA), 48 Seasons NT coaching